The bamboo fiber (BF)-reinforced polylactic acid (PLA) composites were prepared using the twin-screw extruder and injection molding. Thermal gravimetric analyzer results indicated the thermal stability of BF/PLA composites decreased with increasing BF content. Differential scanning calorimeter and X-ray diffraction curves showed that BF played a role as a nucleating agent, but the crystallinity of composite materials decreased with the increasing BF content. The melt flow rate of composites reduced with the increase in BF content, resulting in a poorer processing property. The processability of the composites was improved with the addition of high molecular polyethylene glycol (PEG). Mechanics performance test showed that tensile strength and bending strength of composites increased at low loading with the BF content increased then decreased when the loading continued to increase. The tensile strength of the composite materials reached 65.46 MPa when alkali-treated BF (ABF) content was 20 wt %. The flexural strength of the composites reached 97.94 MPa when ABF content was 10 wt %. Impact performance has also been improved. PEG-20000 was the best plasticizer among the PEG-6000,PEG-10000, and PEG-20000. When the component of PEG was 10 wt %, the elongation increased by 56%. The scanning electron microscopy (SEM) result showed that the fracture of the composites was smooth, most ABF were wrapped in matrix and distribution of ABF in PLA matrix was more uniform. It means that interfacial compatibility of bamboo fiber and PLA improved after BF modified by alkali. High molecular weight PEG enhance melt flow ability of polymer, result in fibers were further enclosed in the PLA matrix and increase properties of composites.
In this work, micrometer copper-zinc alloy particles-reinforced particleboard wood flour/poly (lactic acid) (mCu-Zn/PWF/PLA) wood plastic composites with high gloss and antibacterial properties for 3D printing were prepared by a melt blending process. The structure and properties of the composites with different contents of mCu-Zn were analyzed by means of mechanical testing, dynamic mechanical analysis, thermogravimetric analysis, differential scanning calorimetry, X-ray diffraction, scanning electron microscopy, and antibacterial testing. The results showed that the mechanical properties, thermal stability, and antibacterial performance of the composites were significantly improved, as mCu-Zn was added into the wood plastic composites. When adding 2 wt.% mCu-Zn, the flexural strength of mCu-Zn/PWF/PLA composites (with 5 wt.% of particleboard wood flour) (PWF) increased by 47.1% compared with pure poly (lactic acid) (PLA), and 18.9% compared with PWF/PLA wood plastic composites. The surface gloss was increased by 1142.6% compared with PWF/PLA wood plastic composites. Furthermore, the inhibition rates of mCu-Zn/PWF/PLA composites against Escherichia coli reached 90.43%. Therefore, this novel high gloss and antibacterial wood plastic composites for fused deposition modeling (FDM) 3D printing have potential applications in personalized and classic furniture, art, toys, etc.
A number of polymers have been “cold” extruded (i.e. at temperatures well below their normal melting temperatures) by the application of relatively high pressures. In all cases extrudates of relatively large cross‐sectional area have been produced, and non‐circular cross‐sections have also been extruded. The extruded products has been evaluated and the results discussed. In general it has been found that whilst extrusion gives an oriented product, the increase in tensile modulus is much less than for a comparably drawn fibre. This phenomenon has been discussed in terms of the changes in crystalline structure produced by extrusion.
Lignin microspheres were prepared by the solvent‐anti‐solvent method and blended with pure poly (lactic acid) (PLA) to prepare lignin microspheres/PLA composites for fused deposition modeling. Lignin microspheres were successfully prepared by using deionized water as the anti‐solvent and methanol (MAL), ethanol (EAL), and n‐propanol (NPA) as solvent, respectively. Scanning electron microscopy (SEM) of lignin microspheres showed that the best microspheres were prepared by NPA at 60 C (NPA‐60), with the size range of microspheres between 800 and 1000 nm. Moreover, the lignin microspheres/PLA composites showed the best mechanical properties when 0.375 wt% NPA‐60 was doped into PLA matrix. Compared with pure PLA, the tensile strength, flexural strength and impact strength of the 0.375 wt% NPA‐60/PLA composites were increased by 49.80%, 25.00%, and 112.64%, respectively. Therefore, the lignin microsphere/PLA composites prepared by using a small amount of lignin microspheres as reinforcing filler has excellent mechanical properties, which are ideal 3D printing materials for fused deposition modeling.
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